Method for making a vinyl chloride resin sheet and sheet formed by said method

ABSTRACT

A method for making a vinyl chloride resin sheet having a raised pattern thereon. The method comprises the steps of providing an open-celled vinyl chloride resin sheet and printing a portion of the sheet with a composition comprising a cross-linkable compound in accordance with the pattern to be formed. The printed sheet is then dried and subsequently heated to a temperature higher than its softening temperature whereby the open-celled unprinted portion of the sheet is depressed and whereby the printed pattern remains open-celled and stands in relief with respect to the depressed portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for forming a relief pattern on avinyl chloride resin sheet and to the sheet formed by the method.

2. Description of Prior Art

A variety of processes are known for forming a vinyl chloride resincompounded composition into a formed sheet. Such techniques include acalendering process wherein a vinyl chloride resin compoundedcomposition containing a foaming agent of a well-known type is kneadedand rolled. The resulting article is then heated at such a temperatureand for a length of time such that the foaming agent is decomposed.

According to yet another process, the sheet may be formed by amechanical foaming process wherein a vinyl chloride resin compoundedcomposition is kneaded to give a paste sol and is then mechanicallyagitated while blowing air therein. The resulting foam paste is appliedand then thermaly gelled.

In another process, a paste sol is obtained by kneading a foamingagent-containing vinyl chloride resin. The compounded composition isapplied and thermally gelled under conditions of time and decompositiontemperature of the foaming agent.

Finally, in yet another process a composition is foamed by agitating avinyl chloride resin emulsion compounded composition while blowing airtherein which is applied and then thermally gelled. The foamed sheetthus obtained may be backed with a backing material such as pulp paper,asbestos paper, a fabric, a non-woven fabric, a plywood board, an ironplate or the like, as desired.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for applying apattern to foamed structures.

It is a further object of the invention to provide a method for raisingthe patterned portion of the foamed structure in relief.

These and other objects are fulfilled by means of the method of theinvention for making a vinyl chloride resin sheet having a reliefpattern thereon. The method comprises the steps of providing anopen-celled vinyl chloride sheet and printing a portion of the sheetwith a composition comprising a cross-linkable compound in accordancewith the pattern to be formed. The printed sheet is then dried andheated to a temperature higher than its softening temperature wherebythe open-celled, unprinted portion of the sheet is depressed and wherebythe printed pattern remains open-celled and stands in relief withrespect to the depressed portion.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention relates to a method for making a vinyl chloride sheet witha printed, white-spotted pattern on the surface thereof. The methodcomprises printing the surface of a foamed vinyl chloride resin sheethaving an open cellular structure with an ink containing across-linkable compound in a desired pattern such that the ink isimpregnated or filled into the foamed layer of the resin sheet. Themethod further comprises drying the printed sheet and heating the driedsheet to a temperature higher than its softening temperature wherebyareas printed with an ink containing no cross-linkable compound in adesired pattern as well as non-printed areas are both melted todisintegration and become depressed while areas printed with an inkcontaining the cross-linkable compound remain open-celled in structureand stand in relief.

The method of the invention further relates to a process for making avinyl chloride printed sheet having a printed white-spotted patternwhose open cellular structure is impregnated and filled with a vinylchloride resin paste for reinforcement. The final sheet exhibits anincreased wear resistance and finds utility, for example, as a flooringmaterial.

In one particular embodiment, the invention relates to a methodcomprising the step of processing a vinyl cloride resin composition intoa foamed sheet having an open cellular structure which exhibits air andwater vapor permeability. The method further comprises the step ofprinting the sheet with an ink containing a cross-linkable compoundalong a desired pattern while simultaneously allowing the applied ink orpigment to be impregnated into this sheet. The printed sheet is thenheated to permit the open cellular structure in those areas where nocross-linkable compound is impregnated to be melted and disintegrated.

In one possible embodiment of the invention, the process furthercomprises the step of impregnating or filling the areas of the opencellular structure with a filling of vinyl chloride resin paste and thengelling the impregnated paste.

The sheet itself may be formed by any of the conventional techniques forforming such sheets including the following.

The vinyl chloride resin sheet having the open cellular foam structurecan be made air and water vapor permeable by, for example, a techniquein which air and water vapor permeabilities are imparted to the resinsheet simultaneously by heating a foaming agent in the resin atconditions of time and temperature necessary to foam a foaming agenttherein.

Yet another method for imparting air and water vapor permeability to thesheet is the mechanically frothing process of vinyl chloride plastisol.

Yet another method of rendering the resin sheet air and water vaporpermeable comprises mechanically perforating the sheet-like foam toimpart air and water vapor permeability thereto.

The invention is of course not limited to the particular techniques usedfor imparting permeability and any other conventional techniques maylikewise be used.

According to the invention, the desired pattern is applied by means ofany or a combination of various printing techniques onto the foam sheethaving good air and water vapor permeability while simultaneouslyimpregnating the applied ink. Various techniques including flexoprinting, screen printing, and gravure printing techniques may be usedfor this purpose.

Once the sheet has been printed with the desired pattern, theopen-cellular structure is melted and disintegrated to form a printeddapple by heating the printed sheet in air to a temperature higher thanthe melting and softening temperature of the vinyl chloride resin.

According to one embodiment of the invention, vinyl chloride resin pastemay be impregnated or packed in areas where the open-cellular structuresuffers no disintegration. Such impregnation is feasible by an immersionand compression technique wherein a sheet bearing a printed, dappledpattern thereon is compressed and restored while immersing it in a vinylchloride resin paste so as to allow the impregnation and supplementationof previously impregnated material.

In yet another technique, the paste is applied by an immersion andvacuum suction method in which the vinyl chloride resin paste isimpregnated and deposited under sucking-in-vacuo conditions whileimmersing the sheet, bearing the printed, dappled pattern into thepaste.

The impregnated and deposited vinyl chloride resin paste may be gelledby means of ordinary heating techniques.

As referred to throughout the application, the vinyl chloride resinuseful in the present invention may be one prepared by a suspensionpolymerization or an emulsion polymerization; the preferred degree ofpolymerization being about 700-2,000.

The resin of the invention may obviously comprise any plasticizers,stabilizers, foaming agents, lubricants, antioxidants, fillers, inks orpigments and surface active agents normally used in such formulations.

With respect to plasticizers for the vinyl chloride resin, suchplasticizers may include phthalic esters, phosphoric esters, chlorinatedfatty acid esters, chlorinated paraffin, epoxy compounds, polyesters,adipic esters, and trimellitic esters.

Though the type of stabilizer will vary depending upon the degree ofpolymerization of the resin used and on the amount of plasticizer, sincethe stabilizer influences the decomposition temperature of the foamingagent, composite stabilizers comprising cadmium, barium, zinc, lead,tin, calcium, and organic chelators may be used.

Foaming agents which may be used includedinitrosopentamethylenetetramine, azodicarbonamide,P,P'-oxybisbenzenesulfonylhydrazide, toluenesulfonylhydrazide and thelike.

The lubricant used may be selected as a function of the processingconditions and its desired effect on the foaming properties of thecomposition. Preferably, paraffin, low molecular weight polyolefins,stearic acid, stearic esters, stearyl alcohol, waseline, amides,polyglycol esters of fatty acid and like compounds are used.

If the desired, an antioxidant may be added to the composition. Typicalantioxidants which may be used include phenols, thiopropionic esters,and organic phosphite esters.

The resin may further comprise fillers including calcium carbonate, zincoxide, magnesium oxide, aluminum hydroxide, inorganic spheres, inorganichollow spheres, organic hollow spheres, pulp powder, wood dust, and thelike.

The resin may be pigmented with an ink conventionally employed with suchresins.

In addition to the above additives, a surface active agent foremulsifying the vinyl chloride resin may also be used. Such an agent maybe selected from a group comprising phosphoric monoesters and diesters,polyoxyethylenesorbitanmonooleate, polyoxyethylene lauryl ether,polyethylene glycol monolaurate and the like.

In order to improve the magnifying power of foaming of the vinylchloride resin, as well as the low-temperature characteristics andimpact characteristics of the vinyl chloride resin product, any of thefollowing materials may be added: a polyolefin polymer, a vinylacetate-ethylene copolymer, and acrylonitrile-butadiene copolymer, andacrylic polymer, rosin ester and the like.

The printing ink or pigment used in the invention may be an aqueous ornonaqueous organic ink and is applied to the foamed sheet in animage-wise pattern such that the ink impregnates or fills the sheet fromits surface into the foamed layer.

The vinyl chloride resin paste referred to above for use in reinforcingthe remaining open-celled areas by impregnation, may be prepared by anyconventional technique and is preferably of low viscosity.

In the course of making the foamed sheet having an open cellularstructure which is air and water vapor permeable, the addition to thevinyl chloride resin composition of a metal oxide capable ofaccelerating the cross-liking velocity of the vinyl chloride resin maybe desirable. Thus, the addition of zinc oxide, lead oxide, magnesiumoxide, antimony oxide, zirconium oxide, barium oxide, iron oxide, or tinoxide, contributes to substantially improve the rate and degree ofcross-linkage of the vinyl chloride resin by the cross-linkable ink.

The printed sheet having the open cellular structure described above maybe provided with a transparent protecting layer over its surface so asto protect the printed surface and to increase its durability. In thisinstance, the transparent layer is preferably formed from a hardeningresin such as a two-component polyurethene or a one-componentpolyurethene, or from a mixture of the polyurethene with vinyl chlorideresin.

Cross-linking compounds for cross-linking the vinyl chloride resin ofthe present invention include 2-mercaptoimidazoline, diethylthiourea,trimethylthiourea, tetramethylthiourea,N,N'-diphenylphenylenediamine,diphenylguanidine, isocyanate, trithiocyanuric acid and its derivatives,and mercaptotriazine and its derivatives or their metal salts. Thesecompounds may be used singly or in combination.

The cross-linkable compound which may be incorporated into theopen-celled patterned portion of the sheet include those compoundscapable of vulcanization, those capable of cross-linking and hardeningwith an amine, those capable of cross-linking and hardening by virtureof an inorganic compound such as ammonium chloride, and those capable ofcross-linking and hardening by photopolymerization, as well as mixturesthereof.

Examples of compounds which may be cross-linked by vulcanization includerubbers such as acrylonitrile-styrene-butadiene rubber, chlorosulfonatedpolyethylene rubber, chloroprene rubber and the like, which may in somecases also be cross-linked by a peroxide.

Materials or compounds capable of polymerizing, cross-linking, andhardening by virture of peroxide include monomers, low molecular weightpolymers and prepolymers such as acryl methacrylate, diallyl fumarate,triethylene glycol dimethacrylate, ethylene glycol dimethacryllate,tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate,polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,diallyl phthalate, polyesters having at least two inner olefinicunsaturations, and mixtures thereof.

Compounds which may be cross-linked and hardened by photopolymerizationwhich may be used within the context of the invention include but arenot limitd to, a combination of prepolymers of hexamethylenediamineadipate and ε-caprolactam, N, N'-hexamethylene-bis-methacrylamideserving as a cross-linking agent and a cross-linking initiator such asbenzophenone, a combination of a copolymer of triethylene glycoldimethacrylate, and methylacrylate-P-vinylbenzoic acid and benzoyl ethylether, and the like.

According to one exemplary embodiment of the invention, the vinylchloride resin composition is admixed with anacrylonitriale-butadiene-styrene copolymer, sulfur oxide and zinc oxideto form a foamed sheet having good air and water vapor permeabilities.The sheet is then printed in an image-wise pattern with a printing inkcontaining a vulcanization accelerator such as tetramethylthioureadisulfide, zinc dimethyldithiocarbamate, or the like simultaneouslyimpregnating the sheet with the ink.

In another embodiment of the invention, when using a combination of acompound which is polymerized, vulcanized, and cured with a peroxide,may comprise a combination of diallyl phthalate and a peroxide such asbenzoyl peroxide or tertiary butyl perbenzoate contained in the ink.

In another embodiment, an amine hardener comprising a combination of anepoxy resin such as epoxidized soybean oil and benzyldimethylamine isused. In this instance the epoxy resin is contained in the foamed sheetwhile the benzyldimethylamine is contained in the ink.

In yet other embodiments, urea or melamine, or mixtures or derivativesthereof are examples of compounds which may be hardened with ammoniumchloride or ammonium secondary phosphate. In this embodiment, bothcomponents are contained in the ink.

According to yet another embodiment of the invention, compounds showingvery strong intermolecular bonds with the vinyl chloride resin therebyincreasing viscosity of the resin upon application of heat arethixotropic agents including aluminum stearate, monobenzyl sorbitol,dibenzyl sorbitol, tribenzyl sorbitol, organic complexes such as hydrousaluminum silicate, and the like, and mixtures thereof.

Quite obviously, the air and water vapor permeability of the vinylchloride resin sheet may be increased if desired, by slicing the sheetinto slices having an appropriate thickness.

The invention will now be described with reference to the followingexamples.

EXAMPLE 1

A composition having the following formulation is prepared and appliedto form a layer having a thickness of about 0.7 mm. All quantities arelisted in parts by weight.

    ______________________________________                                        Vinyl Chloride Resin (GENON 121)                                                                     100                                                    Plasticizer (DOP)      60                                                     TCP                    20                                                     Cadminum-barium stabilizer                                                                           5                                                      Foaming agent (VINYFOR AW9)                                                                          5                                                      [Eiwa Chem. Synthetic Co., Ltd]                                               Waseline               10                                                     Silasballoon                                                                  (the microballoon of valcanic rock)                                                                  30                                                     Calcium carbonate      10                                                     Titanium oxide         10                                                     ______________________________________                                    

The coated paper is heated in an air temperature of 190-200 degreescentigrade for three minutes to simultaneously foam and gel the layerthereby resulting in a foam having good air and water vaporpermeabilities. The resulting sheet is then printed with an ink havingthe following formulation by a gravure printing technique such that theapplied ink is permitted to impregnate the sheet.

    ______________________________________                                        Aqueous color ink  10                                                         2-mercaptoimidazoline                                                                            5                                                          Tetramethylthiourea                                                                              5                                                          ______________________________________                                    

The sheet having the printed patten impregnated with ink is heated at atemperature of 180 degrees centigrade for five minutes. As a result, avinyl chloride resin sheet is obtained having a printed, dappled patternin which the printed pattern areas are held open in a cellular structureand are in raised relief while the open cellular structure in thenonprinted areas becomes meltingly disintegrated thus becomingdepressed.

EXAMPLE 2

The following mixture is prepared and applied to a non-woven glassfabric in the form of a layer having a thickness of about 0.7 mm. Allquantities are in parts by weight.

    ______________________________________                                        Vinyl chloride resin (GEON 121)                                                                         100                                                 Plasticizer (DOP)         50                                                  Stabilizer (STABILIZER F[Kyodo Chem.                                                                    5                                                   Co. Ltd.])                                                                    Foaming agent (UNIFOAM AZ-F[Otsuka Chem.                                                                10                                                  Co., Ltd])                                                                    ______________________________________                                    

The coated sheet is heated in an air temperature of about 190 to about200 degrees centigrade for three minutes to simultaneously foam and gelthe layer thereby resulting in a foam having an open cellular structureexhibiting good air and water vapor permeabilities. The sheet is thensubjected to a gravure printing technique using an ink having thefollowing composition while permitting the ink to impregnate the layer.

    ______________________________________                                        Copolymer by suspension                                                                              100                                                    polymerization (GEON 400 × 150ML)                                       Plasticizer (DOP)       50                                                    Stabilizer (ADVASTAB BZ16NT                                                                           4                                                     Katsuta Chem. Co., Ltd.)                                                      Azo red pigment        Suitable amount                                        ANON (Cyclohexanone)   100                                                    MEK (Methyl ethyl ketone)                                                                            500                                                    Dibenzasorbitol (GELOL D                                                                              10                                                    [Shin Nippon Phy. and Chem. Co., Ltd])                                        ______________________________________                                    

The foam having the printed pattern thereon and impregnated with the inkis heated at a temperature of about 190 degrees centigrade for fiveminutes. As a result, a foamed sheet is obtained having a printed,dappled pattern in which the non-printed areas become depressed as aresult of the disintegration of the open cellular structure whereas theprinted pattern areas are colored from the front surface to the back andare in raised relief.

The resulting sheet is then immersed in a vinyl chloride resin pastehaving the following composition.

    ______________________________________                                        Vinyl chloride resin (GEON 25)                                                                      100                                                     Plasticizer (DOP)     50                                                      Stabilizer (ADVASTAB BZ16NT                                                                         5                                                       [Katsuta Chem. Co., Ltd.])                                                    Mineral Spirit        20                                                      ______________________________________                                    

The treated sheet is then repeatedly passed between a metal and rubberroller under pressure.

The paste remaining on the surface of the sheet is wiped off and thesheet is then allowed to stand in air at a temperature of about 160degrees centigrade for a period of five minutes so as to obtain asolid-state printed, dappled pattern bearing sheet in which the paste isimpregnated and filled in the areas of the foam where the open cellularstructure remains.

EXAMPLE 3

A composition having the following formulation is prepared and appliedto a woven fabric in a layer thickness of about 0.5 mm. All quantitiesare listed in parts by weight.

    ______________________________________                                        Vinyl chloride resin (GEON 121)                                                                     100                                                     Plasticizer (DOP)     70                                                      Stabilizer (ADVASTAB ABCIT                                                                          5                                                       [Katsuta Chem. Co., Ltd.])                                                    Foaming agent (VINYLFOR AW9                                                                         5                                                       ]Eiwa Chem. Synthetic Co., Ltd.])                                             Waseline              15                                                      Liquid rubber (NIPOL 1312)                                                                          20                                                      [Nippon Zeon Co., Ltd.])                                                      Sulfur                0.5                                                     Calcium carbonate     10                                                      ______________________________________                                    

The thus coated sheet is heated in an air temperature of about 190 toabout 200 degrees centigrade for three minutes to simultaneously foamand gel the layer so as to obtain a foam having an open cellularstructure exhibiting good air and water permeabilities. The foam issliced into a sheet having a thickness of about 1 mm. The sliced sheetis then subjected to a monochronomatic gravure printing using an inkhaving the following formulation.

    ______________________________________                                        AQUA PS (red) (Product of                                                                           50                                                      Toyo Ink Co., Ltd.)                                                           Zinc dimethyldithiocarbamate                                                                        10                                                      ______________________________________                                    

An ink having the following formulation, using another color, is thenprinted in the course of a second gravure printing.

    ______________________________________                                        AQUA PS (white) (product of                                                                       whole quantity                                            Toyo Ink Co., Ltd.)                                                           ______________________________________                                    

The foam impregnated and printed with the red and white inks is heatedat a temperature of about 190 degrees centigrade for about 5 minutes toobtain a suede-like foam having a printed dapple in raised relief and inwhich the white non-printed areas become depressed as a result of thedisintegration of the open cellular structure while the red areasmaintain their open cellular structure.

Although the invention has been described with respect to particularresins, stabilizers, foaming agents, plasticizers, dies and pigments,and colors, it is to be understood that the invention is not limited tothe particulars disclosed and that substitution of equivalents ispossible without departing from the scope of the claims.

What is claimed is:
 1. A method for making a vinyl chloride resin sheethaving a relief pattern thereon, said method comprising the steps of:(a)providing an open celled vinyl chloride resin sheet; (b) printing aportion of said sheet with a composition comprising a cross-linkablecompound in accordance with said pattern; (c) drying said printed sheet;(d) heating said dried sheet to a temperature higher than its softeningtemperature whereby the open celled unprinted portion of said sheet isdepressed and whereby said printed pattern remains open celled andstands in relief with respect to said depressed portion.
 2. The methodas defined by claim 1 further comprising the step of filling a resinpaste into said patterned portion of said sheet after step (d.)
 3. Themethod as defined by claim 2 further comprising heating said sheetcomprising said resin paste to cross-link said paste so as to strengthensaid sheet.
 4. The method as defined by claim 3 wherein said resin pasteis vinyl chloride resin paste.
 5. The method as defined by claim 1wherein said cross-linkable compound comprises an ink.
 6. The sheetformed by the method of any one of claims 1, 2, 3, 4, or
 5. 7. Themethod as defined by claims 1, 2 or 5 wherein said printing of step (b)comprises flexo printing said compound into said pattern.
 8. The methodas defined by claims 1, 2 or 5 wherein said printing of step (b)comprises screen printing said compound into said pattern.
 9. The methodas defined by claims 1, 2 or 5 wherein said printing of step (b)comprises gravure printing said compound into said pattern.
 10. Themethod as defined by claims 1 or 2 further comprising applying atransparent layer over said raised and depressed portions.
 11. The sheetformed by the method of claim
 10. 12. The method as defined by claims 1or 2 further comprising the step of incorporating an aqueous ink intosaid sheet in accordance with said pattern.
 13. The sheet formed by themethod of claim
 12. 14. The method as defined by claims 1, 2, or 5wherein said cross-linkable compound is selected from the groupconsisting of a compound capable of cross-linking said vinyl chlorideresin; a compound which itself may be cross-linked and cured; a compoundcapable of cross-linking a substance present in said vinyl resin sheet;a compound exhibiting a highly pronounced intermolecular bond with saidvinyl chloride resin and which is capable of substantially raising theviscosity of said vinyl chloride resin when heated; or mixtures thereof.15. The method as defined by claim 14 wherein said cross-linkablecompound is a compound capable of cross-linking a substance present insaid vinyl resin sheet.
 16. The method as defined by claim 15 whereinsaid cross-linkable compound is a member of the group consisting of2-mercaptoimidazoline, diethylthiourea; trimethylthiourea;tetramethylthiourea; N,N'-diphenylphenylenediamine; diphenylguanidine;isocyanate; trithiocyanuric acid and its derivatives; mercaptotriazineand its derivatives; metal salts of mercaptotriazine and mixturesthereof.
 17. The method as defined by claim 14 wherein saidcross-linkable compound is a compound which may itself be cross-linkedand cured.
 18. The method as defined by claim 17 wherein saidcross-linkable compound is a member of the group consisting of: acompound capable of cross-linking by vulcanization; a compound capableof being cross-linked by a peroxide; a compound which is cross-linkableand hardenable with an amine; a compound capable of being cross-linkedand hardened with an inorganic compound; a compound capable of beingcross-linked and hardened by photopolymerization; and mixtures thereof.19. The method as defined by claim 18 wherein said cross-linkablecompound is a compound capable of cross-linking by vulcanization. 20.The method as defined by claim 18 wherein said cross-linkable compoundis a rubber selected from the group consisting ofacrylonitrile-butadiene-styrene rubber; chlorosulfonated polyethylenerubber; chloroprene rubber and mixtures thereof.
 21. The method asdefined by claim 20 wherein said cross-linkable compound is a compoundcapable of being cross-linked by a peroxide.
 22. The method as definedby claim 24 wherein said cross-linkable resin is a monomer, lowmolecular weight polymers and prepolymers selected from the groupconsisting of: acryl methacrylate; diallyl fumarate; triethylene glycoldimethacrylate; ethylene glycol dimethacryllate; tetraethylene glycoldimethacrylate; 1,3-butylene glycol dimethacrylate; polyethylene glycoldimethacrylate; trimethololpropane trimethacrylate; diallyl phthalate;polyesters having at least two inner olefinic unsaturations; andmixtures thereof.
 23. The method as defined by claim 17 wherein saidcross-linkable compound is cross-linkable and hardenable with an amine.24. The method as defined by claim 23 wherein said amine isbenzyldimethylamine.
 25. The method as defined by claim 17 wherein saidcross-linkable compound is cross-linkable and hardenable with aninorganic compound.
 26. The method as defined by claim 25 wherein saidinorganic compound is ammonium chloride or ammonium secondary phosphateand said cross-linkable compound is urea or melamine or mixtures orderivatives thereof.
 27. The method as defined by claim 17 wherein saidcross-linkable compound is cross-linkable and hardenable byphotopolymerization.
 28. The method as defined by claim 27 wherein saidcross-linkable compound is selected from the group consisting ofhexamethylenediamine adipate and ε-caprolactam.
 29. The method asdefined by claim 17 wherein said cross-linkable compound is a compoundexhibiting a highly pronounced intermolecular bond with said vinylchloride resin and which is capable of substantially raising theviscosity of said vinyl chloride resin when heated.
 30. The method asdefined by claim 29 wherein said cross-linkable compound is selectedfrom the group consisting of: aluminum stearate; monobenzyl sorbitol;dibenzyl sorbitol; tribenzyl sorbitol; hydrous aluminum silicate; andmixtures thereof.